[TowerTalk] 160 meter directive array at K3LR - W8WWV notes

[Jon Zaimes, AA1K]

Thanks to Greg for this thorough analysis.
I'm still absorbing it all but one thing that struck me was this in the consideration of optimizing:
"The one thing that can’t be changed is the location of the parasitic elements. They are located over extensive radial systems with miles of wire that can’t be moved."
I think moving the elements in one of several ways could provide an increase in gain. Certainly achievable if one were starting to build this from scratch.
In my own case I added a second director toward Europe for a theoretical extra 0.9 db gain.
But what got me thinking of modifying the other elements was an article by K0HA (Bill in Nebraska) that described his 5-element parasitic arrays made of BX tower in the 1970's or '80s. I believe he found 80-foot spacing to be the optimum.
In another vertical array I have, a broadside-endfire for 80 meters, I nested it inside a 160m broadside-endfire array and simply tapped into a single radial of the 160m array radial field for each 80-meter feedpoint. Impedance measurements were similar to what I would expect from having the radials all terminating at the 80m feedpoints. Performance has been good.
So could we simply move move the K3LR array feedpoints outward without moving the radial field, tying into a single radial?
I started building my 160-meter version of the K3LR array in 1998, after reading about it in ON4UN's book and some earlier articles on sloping 2-element reflectors or directors hung off a driven tower. Initially the parasitics used the sloping "T" top.
But after I added three other towers in strategic positions these held up the end of the ropes and the top of these T elements became horizontal. The NW element remains a sloping T. I have pondered shifting the T tops outward from the tower if this could produce more gain, with the vertical wire sloping away from the tower.
Another option I've thought about is pulling the vertical portion of the wire outward from the tower, perhaps 20-30 feet up from the feedpoint. 
Next summer I'm planning a re-do of my array and may experiment with some of these.
73/Jon

Jon P. Zaimes, AA1K
Tower climber for hire
Felton, Delaware
http://www.aa1k.us/
Cell: 302-632-2353 

Reviews of AA1K tower work on eham website: http://www.eham.net/reviews/detail/12922

Hug your favorite tower every day, and always stay connected to it. 

    On Sunday, November 10, 2024 at 11:18:49 AM EST, Tim Duffy <k3lr at k3lr.com> wrote:   

 The 160 meter three element vertical parasitic array that we use at K3LR has
been published (details on how to build) in the last three editions of the
ON4UN Low Band DXing book. Since I have used this antenna for 30 years,
several stations such as K9CT, VE3EJ, AA1K, W5ZN and NR5M now use this
antenna. Greg, W8WWV recently did some investigative modeling work about the
antenna - which is presented here:

 <http://www.k3lr.com/engineering/160m/K3LR160m2024Revisit.pdf>
K3LR160m2024Revisit

 

73

Tim K3LR

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